Midget Speedo

My last spare Midget Speedometer is reading all crazy now so i need to find a replacement and i have been looking at replacing it with an autometer drop in gauge. They are the same exact size so i would not have to cut anything and i am hoping the autometer will work longer than a year or two (unlike the smiths) Im not sure whats wrong with mine but i have put 3 speedos and a cable on this car and they keep going bad, im tired of it. What i need to know is how big both ends of the cable are, and also what kind of setup the datsun transmission uses as i will move to a 5 speed when i have the time and money to convert. I may go with an electric model but the cable speedos are a little cheaper. Whats your opinion on this plan?

Dr.

If you've replaced all those parts with new parts, you have another problem & putting a different speedo in won'ty solve it....question to ask is: What's causing all those speedo's/cables to go bad? Have you looked at your gears in tranny? Are you supposed to have an angle drive on either or both ends cable?

Im not sure how its supposed to be. i had a couple spares laying around with lots of miles on them so i havent ever really started with a new speedo head. One of them the needle fell off, one was really jumpy, and the current one reads about 20mph too fast. The cable i replaced looked good and the one i put in is identical to the one i took out. Doesnt mean its the right one though. As for the tranny gear, i dont recall ever looking at it. When i swapped speedos the ones i put in worked for a while, and then stopped. I guess i should research this problem further. I was just figuring my 30 year old gauges are worn out.

Dr.

Hello Dr E,
most speedo troubles are due to cables, especially if the needle jumps.
Reference the 20mph too fast, it is probably the wrong unit. Smiths speedos have a number on the dial at the bottom giving the cable revolutions per mile.

Alec